Rotatable Shielding Member for Fixing Device Heat Control
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face issues with excessive heating of shielding members, leading to potential deformation and reduced functionality, as well as prolonged startup times due to the need to return shielding members to their initial position after interruptions or maintenance.
Innovation Solution
A fixing device with a rotatable shielding member that moves between a shielding position and a retraction position, where the rotation center is positioned differently from the heating source, and an initial position detecting unit that allows for quick return to the initial position, reducing the need for extensive movement and minimizing heat exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a shielding member is provided to block heat from the heating source in the non-paper feeding region, then the temperature of the fixing member can be controlled, but the shielding member itself is heated and may be deformed
Solution Approach 1:
A reflecting member is introduced as an intermediary between the heating source and the shielding member. The reflecting member reflects heat from the heating source toward the fixing member, while the shielding member blocks this reflected heat. This intermediary arrangement allows the shielding member to perform its temperature control function without being directly exposed to the heating source, thereby preventing deformation and improving reliability.
2Adaptability or versatility
If the shielding member is made movable to be disposed at an appropriate position according to paper sheet size, then heat can be blocked in a necessary range, but time is required to return the shielding member to the initial position after interruptions
Solution Approach 1:
The system performs preliminary actions by detecting paper sheet size in advance and positioning the shielding member at the appropriate position before the fixing operation begins. This eliminates the need to move the shielding member during operation and reduces the time required to return it to the initial position after interruptions, as the system can quickly reset to a predefined position rather than recalculating and repositioning.
3Ease of operation
If the shielding member is rotatably supported to enable movement, then positioning flexibility is improved, but the support structure becomes complicated and increases in size
Solution Approach 1:
Instead of making the shielding member itself rotatable with complex support structures, the invention inverts the approach by making the heating source rotatable. The reflecting member and shielding member remain stationary, while the heating source rotates to adjust the heat blocking range. This inversion simplifies the support structure significantly, as the rotating heating source requires minimal support mechanisms compared to a rotatable shielding member.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses heating of the shielding member, preventing deformation and improving reliability, while also reducing the startup time by enabling faster positioning of the shielding member.
Implementation Method 1
a fixing member (21) heated by a heating source (23) such as a heater
Implementation Method 2
a shielding member (27) configured to block heat from the heating source (23)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A fixing device (20) includes a rotatable fixing member (21) ; a heating source (23) configured to heat the fixing member (21); an opposing member (22) configured to come into contact with an outer circumferential surface of the fixing member (21) to form a nip portion (N); and a shielding member (27) configured to block heat from the heating source (23). The shielding member (27) is configured to rotate about a position different from the center of the heating source (23) so as to be movable between a shielding position and a retraction position. The shielding position is a position where the shielding member comes close to the heating source (23) to block heat from the heating source (23) to the fixing member (21). The retraction position being a position where the shielding member (27) is retracted away from the shielding position.